Blower fan

ABSTRACT

A blower fan includes a motor unit including a rotary unit; a plurality of blades fixed to an outer surface of the rotary unit and arranged to be rotated about a center axis by the motor unit; and a lower plate portion defined by a magnetic body and positioned below the motor unit and the blades. The lower plate portion includes a motor fixing portion, a curved portion, a peripheral portion, and a plurality of ribs arranged to interconnect the motor fixing portion and the peripheral portion either directly or through the curved portion, the curved portion including a standing portion extending upward from the outer edge portion of the motor fixing portion and an upper surface portion extending radially outward from an upper end of the standing portion, a plurality of openings positioned below the blades being defined by the curved portion, the peripheral portion, and the ribs.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a blower fan arranged to blow air.

2. Description of the Related Art

Blower fans are conventionally arranged within the housings of various kinds of electronic devices or home electric appliances. For example, U.S. Patent Application Publication No. 2006-0273667 discloses a motor for use in a cooling fan or the like. The motor includes a base, a rotor, and a balancing member as a magnetic member. The balancing member is fixed to the upper surface of the base and has a plurality of extension portions extending radially outward. The rotor is arranged at the upper side of the base through a bearing. In the motor, the ring-shaped magnet provided in the rotor is axially opposed to the extension portion of the balancing member. A magnetic attraction force is generated between the extension portion and the magnet. This makes it is possible to reduce vibration caused by the rotation of the motor.

In another conventional disk drive motor disclosed in Japanese Patent Application Publication No. 2001-57755, a base plate includes a disc-shaped base portion and a rotor guide piece extending upward from the base portion. The rotor guide piece is axially opposed to a ring-shaped permanent magnet of a rotor. During rotation of the motor, a magnetic attraction force is generated between the permanent magnet and the rotor guide piece. The rotor makes stable rotation under the guidance of the rotor guide piece. This makes it is possible to reduce rotational vibration of the rotor. In a hard disk drive motor shown in FIG. 3 of Japanese Patent Application Publication No. 2005-192313, a circumferentially-extending rib-shaped protrusion is formed in the bottom portion of a base. The protrusion is vertically opposed to a magnet portion of a rotor unit. During the rotation of the motor, the lifting amount of the rotor unit can be adjusted by an attraction force generated between the protrusion and the magnet portion.

In a blower fan, however, a force may be applied to a rotary unit in a direction that the rotary unit is moved away from a base due to an impact applied from the outside and the vibration generated during the operation of the blower fan. In this blower fan, a magnetic member vertically opposed to the lower surface of a rotor magnet is attached on the base whereby a magnetic attraction force is generated between the magnetic member and the rotor magnet. As a result, the rotary unit is prevented from moving in an axial direction. However, a blower fan having an intake or exhaust opening on the lower side thereof has a lower structure that is more complex than a blower fan having no opening. For that reason, if a magnetic member is provided in such a blower fan, the complexity of the lower structure of the blower fan becomes even greater and the number of parts required for the blower fan grows higher.

SUMMARY OF THE INVENTION

Preferred embodiments of the present invention provide a blower fan with an opening at a lower side thereof, which is arranged to restrain axial movement of a rotary unit through the use of a simple structure.

In accordance with a preferred embodiment of the present invention, a blower fan includes a motor unit including a rotary unit; a plurality of blades fixed to an outer surface of the rotary unit of the motor unit and rotated about a center axis by the motor unit; and a lower plate portion defined by a magnetic body and positioned below the motor unit and the blades, wherein the lower plate portion preferably includes a motor fixing portion to which the motor unit is fixed, a curved portion provided in an outer edge portion of the motor fixing portion, a peripheral portion and a plurality of ribs arranged to interconnect the motor fixing portion and the peripheral portion either directly or through the curved portion, the curved portion being arranged below a rotor magnet of the rotary unit to annularly extend about the center axis, the curved portion including a standing portion extending upward from the outer edge portion of the motor fixing portion and an upper surface portion extending radially outward from an upper end of the standing portion, a plurality of openings positioned below the blades being defined by the curved portion, the peripheral portion and the ribs.

With such a configuration, it is possible to restrain axial movement of a rotary unit through the use of a simple structure.

The above and other elements, features, steps, characteristics and advantages of the present invention will become more apparent from the following detailed description of the preferred embodiments with reference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view showing a blower fan according to a preferred embodiment of the present invention.

FIG. 2 is a plan view of a lower plate portion of the blower fan according to a preferred embodiment of the present invention.

FIG. 3 is a partially enlarged sectional view of the blower fan.

FIG. 4 is a partially enlarged plan view of the lower plate portion.

FIG. 5 is a sectional view of a blower fan according to another preferred embodiment of the present invention.

FIG. 6 is a sectional view of a blower fan according to a further preferred embodiment of the present invention.

FIG. 7 is a sectional view of a blower fan according to another further preferred embodiment of the present invention.

FIG. 8 is a perspective view of a lower plate portion according to yet another further preferred embodiment of the present invention.

FIG. 9 is a plan view of the lower plate portion shown in FIG. 8.

FIG. 10 is a sectional view of a blower fan according to a still further preferred embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In this description, the upper side along a center axis of a motor in FIG. 1 will be just referred to as “upper” and the lower side as “lower”. The up-down direction is not intended to mean the positional relationship or orientation of a blower fan with respect to gravity when installed within an actual device. The direction parallel or substantially parallel to the center axis will be referred to as “axial”, the direction perpendicular or substantially perpendicular to the center axis will be referred to as “radial”, and the direction running around the center axis will be referred to as “circumferential”.

FIG. 1 is a sectional view showing a blower fan 1 according to one preferred embodiment of the present invention. The blower fan 1 is a centrifugal fan and is preferably used to cool electronic parts arranged within, e.g., a notebook PC. The blower fan 1 preferably includes a plurality of blades 11, a motor unit 12 and a housing 13. The blades 11 extend radially outward from the motor unit 12. The blades 11 are rotated about a center axis J1 by the motor unit 12.

The housing 13 accommodates the motor unit 12 and the blades 11. The housing 13 preferably includes an upper plate portion 131, a lower plate portion 132, and a sidewall portion 133. The upper plate portion 131 is preferably made of, for example, metal. The upper plate portion 131 is positioned above the motor unit 12 and the blades 11. The upper plate portion 131 preferably includes a single intake port 151 axially overlapping with the blades 11 and the motor unit 12. The intake port 151 will be hereinafter referred to as “upper intake port 151”. The upper intake port 151 has a substantially circular shape about the center axis J1.

The lower plate portion 132 is preferably formed by pressing a magnetic body, for example. The lower plate portion 132 is positioned below the motor unit 12 and the blades 11. A plurality of openings 152 arranged as intake ports are preferably defined in the lower plate portion 132. The openings 152 will be hereinafter referred to as “lower intake ports 152”. The lower intake ports 152 are positioned below the blades 11. The sidewall portion 133 is preferably made of, for example, resin. The sidewall portion 133 covers the side area of the blades 11. The upper plate portion 131 is fixed to the upper end of the sidewall portion 133 preferably by, for example, screws or other fixing apparatus. The lower end of the sidewall portion 133 is preferably combined with the lower plate portion 132 by being embedded therein through, for example, insert molding. In the blower fan 1, an exhaust port 153 shown at the right side in FIG. 1 is defined by the upper plate portion 131, the lower plate portion 132, and the sidewall portion 133. The sidewall portion 133 may alternatively be provided by a method other than insert molding and may be made of a material other than resin.

The motor unit 12 is preferably an outer rotor type. The motor unit 12 preferably includes a stationary unit 21 and a rotary unit 22. The stationary unit 21 preferably includes a sleeve 23 arranged as a bearing, a bearing holder 24, a stator 210, and a circuit board 25. The sleeve 23 includes a substantially cylindrical shape about the center axis J1. The sleeve 23 is preferably an oil-containing porous metal body. The bearing holder 24 preferably has a substantially cylindrical shape about the center axis J1, the bearing holder 24 having a bottom. The bearing holder 24 is arranged to hold the sleeve 23 therein. The bearing holder 24 is preferably made of resin. The lower end of the bearing holder 24 is combined, preferably through insert molding, with a central hole portion 327 provided at the center of a motor fixing portion 31. The bearing holder 24 may alternatively be formed by a method other than insert molding and may be made of a material other than resin if so desired.

The stator 210 preferably has a ring shape about the center axis J1 and is attached to the outer surface of the bearing holder 24. The stator 210 preferably includes a stator core 211, an insulator 212, and coils 213. The stator core 211 is preferably formed by laminating thin silicon steel plates one above another, but any other desirable stator forming method could be used instead. The insulator 212 is preferably an insulating body arranged to cover the surface of the stator core 211. The coils 213 are preferably defined by winding conductive wires on the insulator 212. The circuit board 25 is fixed to the lower portion of the insulator 212. Thus, the lead wires extending from the stator 210 can be easily connected to the circuit board 25.

The rotary unit 22 preferably includes a shaft 221, a rotor holder 222, a yoke 223, and a rotor magnet 224. The shaft 221 is inserted into the sleeve 23 and is rotatably supported by the sleeve 23. The rotor holder 222 preferably has a substantially cylindrical shape about the center axis J1, the rotor holder 222 including a cover. The upper end portion of the shaft 221 is fixed to the cover of the rotor holder 222. The blades 11 extend radially outward from the outer surface 222 a of the rotor holder 222. The rotor holder 222 and the blades 11 are preferably provided as a single monolithic member. In other words, the blades 11 are kept fixed to the outer surface 222 a of the rotor holder 222. A portion 111 of a lower edge 11 a of each of the blades 11 adjoining to the center axis J1 extends from the outer surface 222 a of the rotor holder 222 in a perpendicular or substantially perpendicular relationship with the center axis J1. The portion 111 will be hereinafter referred to as “straight portion 111”. A radial outer portion 112 of the lower edge 11 a is positioned lower than the straight portion 111. The shape of an upper edge 11 b of each of the blades 11 is the same or substantially the same as the vertically inverted shape of the lower edge 11 a.

The yoke 223 has a substantially cylindrical shape about the center axis J1 and is fixed to the inner surface of the rotor holder 222. The rotor magnet 224 has a substantially cylindrical shape about the center axis J1 and is fixed to the inner surface of the yoke 223.

In the motor unit 12, electric power is supplied to the stator 210 whereby a torque about the center axis J1 is generated between the rotor magnet 224 and the stator 210. Thus, the rotary unit 22 and the blades 11 are rotated about the center axis J1. Upon rotation of the blades 11, air is drawn into the housing 13 through the upper intake port 151 and the lower intake ports 152 and is discharged through the exhaust port 153.

FIG. 2 is a plan view of the lower plate portion 132. The upper side in FIG. 2 corresponds to the right side in FIG. 1. The lower plate portion 132 preferably includes a motor fixing portion 31, a curved portion 32, a plurality of ribs 33, and a peripheral portion 34. The motor fixing portion 31 has a substantially circular shape. The motor unit 12 is fixed to the motor fixing portion 31. The motor fixing portion 31 includes a plurality of circular small hole portions 313 and a large hole portion 314 defined around a central hole portion 327.

The curved portion 32 is provided in the outer edge portion 311 of the motor fixing portion 31. When seen in a plan view, the curved portion 32 extends annularly about the center axis J1. A certain region 312 of the outer edge portion 311 of the motor fixing portion 31 preferably has a radially inwardly cut shape. The curved portion 32 is not present in the region 312. The region 312 will be hereinafter referred to as “curved portion nonexistence region 312”.

FIG. 3 is a sectional view showing the portions of the blower fan 1 positioned below the rotor magnet 224. The curved portion 32 preferably includes a standing portion 321 and an upper surface portion 322. The standing portion 321 extends upward from the outer edge portion 311 of the motor fixing portion 31. The upper surface portion 322 extends radially outward from the upper end of the standing portion 321.

A radial outer end portion 322 a of the upper surface portion 322 is positioned between the outer surface 222 a of the rotor holder 222 and the outer surface 224 a of the rotor magnet 224 in the radial direction. The radial outer portion 112 of the lower edge 11 a of each of the blades 11, i.e., the lowermost portion of each of the blades 11, is positioned lower than the upper surface portion 322.

As shown in FIG. 2, the ribs 33 are arranged at a regular interval in the circumferential direction. When seen in a plan view, the ribs 33 are angled with respect to the radial direction. As illustrated in FIG. 3, the ribs 33 are angled downward as they extend radially outward from the radial outer end portion 322 a of the upper surface portion 322. The angle of inclination of the ribs 33 with respect to the horizontal direction makes it is possible to reduce the draft resistance caused by the ribs 33. The ribs 33 interconnect the motor fixing portion 31 and the peripheral portion 34 through the curved portion 32. The peripheral portion 34 is positioned lower than the upper surface portion 322 of the curved portion 32 in the axial direction. The radial outer end portion of the peripheral portion 34 is fixed to the lower end portion of the sidewall portion 133 shown in FIG. 1. As can be seen in FIGS. 2 and 3, the lower intake ports 152 are defined in the lower plate portion 132 by the curved portion 32, the ribs 33 and the peripheral portion 34.

The outer shape of the upper plate portion 131 shown in FIG. 1 is substantially the same as the outer shape of the lower plate portion 132 from which the motor fixing portion 31, the curved portion 32 and the ribs 33 are removed.

FIG. 4 is an enlarged plan view of the motor fixing portion 31. As indicated by double-dot chain lines in FIG. 4, the circuit board 25 preferably includes a circular portion 251 and a projection portion 252. The circular portion 251 is positioned inside the curved portion and above the motor fixing portion 31. The axial position of the circuit board 25 is substantially the same as the axial position of the curved portion 32 in the axial direction. The projection portion 252 protrudes from the circular portion 251 toward the curved portion nonexistence region 312. An integrated circuit 26 is attached to the lower surface of the projection portion 252 and is positioned within the curved portion nonexistence region 312. Electronic parts and downwardly protruding pins (not shown) are preferably positioned on the lower surface of the circular portion 251 in an opposing relationship with the hole portions 313 and 314 of the motor fixing portion 31. If necessary, the electronic parts and the pins are inserted into the hole portions 313 and 314. By providing the hole portions 313 and 314, it is possible to avoid interference of the motor fixing portion 31 with the circuit board 25 having electronic parts and the like and allows the motor fixing portion 31 and the circuit board 25 to come close to each other. As a result, it becomes possible to reduce the thickness of the blower fan 1.

As shown in FIG. 3, the rotor magnet 224 is arranged to be axially opposed to the upper surface portion 322 of the curved portion 32. A magnetic attraction force is generated between the rotor magnet 224 and the upper surface portion 322. Since the upper surface portion 322 substantially annularly extends about the center axis J1, the magnetic attraction force is substantially uniformly generated in the circumferential direction between the rotor magnet 224 and the upper surface portion 322. Accordingly, it is possible to prevent upward movement of the rotary unit 22 even if an upwardly-acting force, i.e., a force pulling the rotary unit 22 away from the motor fixing portion 31, is exerted on the rotary unit 22 due to the impact applied from the outside or the vibration generated during the operation of the blower fan 1. As a result, the rotary unit 22 is prevented from fluctuating.

As described above, by providing the curved portion 32 in the blower fan 1, it is possible to easily generate a thrust load acting on the rotary unit 22. As compared with a blower fan in which a magnetic member vertically opposed to a rotor magnet is additionally provided on a motor fixing portion, it is possible to prevent axial movement of the rotary unit 22 through the use of a simple structure. It is also possible to reduce the number of parts and the manufacturing cost. As compared with a blower fan provided with a magnetic member, it is possible to reduce the thickness of the blower fan 1. Since a thrust load is applied to the rotary unit 22 in the blower fan 1, it is possible to reduce electromagnetic noises as compared with a case of using a so-called magnetic offset by which the axial magnetic center of the stator 210 is offset downward from the magnetic center of the rotor magnet 224. While it is preferred in the blower fan 1 that the magnetic center of the stator 210 axially coincides with the magnetic center of the rotor magnet 224, the magnetic offset may be used in combination insofar as electromagnetic noises do not matter.

Since the ribs 33 extend radially outward from the upper surface portion 322 of the curved portion 32, it is possible to place the curved portion 32 in the formation positions of the ribs 33. This makes it is possible to sufficiently generate a magnetic attraction force between the rotor magnet 224 and the upper surface portion 322 positioned below the rotor magnet 224. Since the ribs 33 are angled downward as they extend radially outward, it is possible to secure a space for the radial outer portions of the blades 11. Since the lowermost portion of the lower edge 11 a of each of the blades 11 is positioned lower than the upper surface portion 322, it is possible to increase the blade area and the air intake and exhaust amount. Due to the fact that the radial inner portions of the ribs 33 are positioned higher than the motor fixing portion 31 and peripheral portion 34, it is possible to broaden the air flow path at the lower side of the blower fan 1 and to efficiently perform the intake of air through the lower intake ports 152.

Preferably, the radial outer end portion 322 a of the upper surface portion 322 is provided radially between a radial outer end point 111 a of the straight portion 111 of each of the blades 11 and the outer surface 224 a of the rotor magnet 224 as shown in FIG. 3. The position of the radial outer end portion 322 a may radially coincide with the position of the outer surface 224 a of the rotor magnet 224. This makes it is possible to sufficiently secure the magnetic action while reducing the draft resistance. More preferably, the radial outer end portion 322 a is positioned between the outer surface 222 a of the rotor holder 222 and the outer surface 224 a of the rotor magnet 224. Alternatively, the position of the radial outer end portion 322 a may radially coincide with the position of the outer surface 222 a of the rotor holder 222 or the position of the outer surface 224 a of the rotor magnet 224. This makes it is possible to further reduce the draft resistance. This holds true in another preferred embodiment of the lower plate portion to be described below.

FIG. 5 is a view showing another preferred embodiment of the lower plate portion. A lower plate portion 132 a is provided with an upwardly-raised curved portion 32 a. The curved portion 32 a preferably includes a standing portion 321, an upper surface portion 322 and a descending portion 323. The standing portion 321 extends upward from the outer edge portion 311 of the motor fixing portion 31. The upper surface portion 322 extends radially outward from the upper end of the standing portion 321. The descending portion 323 extends downward from the radial outer end of the upper surface portion 322. The ribs 33 extend radially outward from the lower end of the descending portion 323.

The curved portion 32 a extends substantially annularly about the center axis J1 at the lower side of the rotor magnet 224. A magnetic attraction force is substantially uniformly generated in the circumferential direction between the rotor magnet 224 and the upper surface portion 322. By providing the curved portion 32 a in the blower fan 1, it is possible to substantially prevent axial movement of the rotary unit 22 through the use of a simple structure.

In the lower plate portion 132 a, the ribs 33 are connected to the lower end of the descending portion 323, whereby the entire portions of the ribs 33 can be positioned sufficiently lower than the upper surface portion 322. As a result, it is possible to easily secure a space for the blades 11. The radial outer portion 112 of the lower edge 11 a of each of the blades 11 is positioned lower than the upper surface portion 322 of the curved portion 32. It is therefore possible to increase the blade area and the air intake and exhaust amount.

FIG. 6 is a view showing a further preferred embodiment of the lower plate portion. In a lower plate portion 132 b, the ribs 33 extend from the upper surface portion 322 of the curved portion 32 in a perpendicular or substantially perpendicular relationship with the center axis J1. A radial inner portion 341 of the peripheral portion 34 extends upward and is connected to the radial outer end portions of the ribs 33.

In the lower plate portion 132 b, the ribs 33 connected to the upper surface portion 322 are perpendicular or substantially perpendicular to the center axis J1, whereby the entire portions of the ribs 33 can be positioned above the motor fixing portion 31 and the peripheral portion 34. Thus, a space 154 is defined below the ribs 33. If the blower fan 1 is arranged in a narrow space within a device, the motor fixing portion 31 and the peripheral portion 34 adjoin to the inner surface 9 of the device. Since air is guided from the space 154 toward the lower intake ports 152, it is possible to efficiently perform the intake of the air through the lower intake ports 152. Inasmuch as the ribs 33 are positioned closer to the portion of the outer surface 222 a of the rotor holder 222 from which the blades 11 extend, it is possible to reduce the draft resistance caused by the ribs 33.

FIG. 7 is a view showing a still further preferred embodiment of the lower plate portion. In a lower plate portion 132 c, the motor fixing portion 31 is positioned higher than the peripheral portion 34. When the peripheral portion 34 adjoins to the inner surface 9 of a device, a large space 155 is defined between the motor fixing portion and the inner surface 9. Accordingly, even when the blower fan 1 is arranged in a narrow space of a device, it is possible to efficiently perform the intake of air through the lower intake ports 152. The existence of the space 155 at the lower side of the motor fixing portion 31 makes it is possible to reduce the draft resistance caused by the motor fixing portion 31 and the ribs 33. In the lower plate portion 132 c, the peripheral portion 34 is largely spaced apart downward from the rotary unit 22. It is therefore possible to easily secure a space for the blades 11.

FIG. 8 is a perspective view showing a still further preferred embodiment of the lower plate portion. The sidewall portion 133 fixed to the lower plate portion 132 d is also shown in FIG. 8. FIG. 9 is a plan view of the lower plate portion 132 d and the sidewall portion 133. The upper side in FIG. 9 corresponds to the left lower side in FIG. 8. The lower plate portion 132 d preferably includes a circular motor fixing portion 31, a plurality of bent pieces 35, a plurality of ribs 33, and a peripheral portion 34. The ribs 33 extend radially outward from the outer edge portion 311 of the motor fixing portion 31. Each of the bent pieces 35 preferably includes a standing portion 351 and an upper surface portion 352. The standing portion 351 is provided in the outer edge portion 311 of the motor fixing portion 31 between the adjoining ribs 33 and extends upward from the outer edge portion 311. The upper surface portion 322 has an arc shape about the center axis J1 and extends radially outward from the upper end of the standing portion 351.

In the lower plate portion 132 d, the bent pieces 35 are arranged on the outer edge portion 311 of the motor fixing portion 31 at a regular interval in the circumferential direction, thereby forming a curved portion 32 b having a substantially ring shape about the center axis J1. When the blower fan 1 is assembled, the curved portion 32 b is positioned below the rotor magnet 224. A magnetic attraction force is generated between the curved portion 32 b and the rotor magnet 224. This makes it is possible to prevent the rotary unit 22 from moving upward.

In the lower plate portion 132 d, the ribs 33 directly interconnect the motor fixing portion 31 and the peripheral portion 34. Therefore, the ribs 33 can be made flush with the motor fixing portion 31 and the peripheral portion 34. As a result, it is possible to easily secure a space for the blades 11 at the upper side of the ribs 33.

While certain preferred embodiments of the present invention have been described above, the present invention is not limited to the foregoing preferred embodiments but may be modified in many different forms. For example, as shown in FIG. 10, a portion 324 extending upward from the radial outer end portion of the upper surface portion 322 may be provided in the curved portion 32. In this case, the rotor magnet 224 protrudes downward beyond the rotor holder 222, whereby a magnetic attraction force can be generated between the lower portion of the rotor magnet 224 and the portion 324 of the curved portion 32 in the radial direction. It is therefore possible to reliably prevent the rotary unit 22 from moving upward. In FIG. 10, the portion 324 may be positioned a little radially outward of the rotor holder 222. In this case, downwardly-flowing air is guided into the motor unit 12 through a space between the curved portion 32 and the rotor holder 222, thereby cooling, for example, the circuit board 25.

In the motor fixing portion 31, cutout portions arranged to receive electronic parts and the like arranged on the lower surface of the circuit board 25 may be provided in place of the hole portions 313 and 314. While three ribs are preferably included in the foregoing preferred embodiments, the number of the ribs 33 may be two or any other number greater than three if so desired.

In the blower fan 1, the upper plate portion 131 may be formed by die-casting aluminum, zinc, or other metals or may be molded resin, for example. In these cases, the upper plate portion 131 may be formed into an outer shape greatly differing from that of the lower plate portion 132. If the upper plate portion 131 is made of molded resin, it is preferred that the upper plate portion 131 be continuously joined to the sidewall portion 133. The technique of preventing movement of the rotary unit 22 through the use of the curved portion 32, 32 a, or 32 b may be applied to a blower fan in which air is drawn through only the lower intake ports 152. This technique may also be applied to a fan that does not have the upper plate portion 131 and the sidewall portion 133. In this case, the members of a device accommodating the blower fan 1 serve as a sidewall portion and an upper plate portion. The technique of preventing movement of the rotary unit 22 through the use of the curved portion 32, 32 a, or 32 b may be applied to other blower fans such as an axial flow fan.

The configurations of the foregoing preferred embodiments and the modified examples may be appropriately combined unless contradictory to one another.

The blower fan according to the present invention can be used in cooling electronic parts within a housing or in feeding air to different objects. Moreover, the blower fan can be used for other purposes.

While preferred embodiments of the present invention have been described above, it is to be understood that variations and modifications will be apparent to those skilled in the art without departing from the scope and spirit of the present invention. The scope of the present invention, therefore, is to be determined solely by the following claims. 

1. A blower fan, comprising: a motor unit including a rotary unit; a plurality of blades fixed to an outer surface of the rotary unit of the motor unit and arranged to be rotated about a center axis by the motor unit; and a lower plate portion defined by a magnetic body and positioned below the motor unit and the blades; wherein the lower plate portion includes a motor fixing portion to which the motor unit is fixed, a curved portion provided in an outer edge portion of the motor fixing portion, a peripheral portion, and a plurality of ribs arranged to interconnect the motor fixing portion and the peripheral portion either directly or through the curved portion; the curved portion is arranged below a rotor magnet of the rotary unit to annularly extend about the center axis, the curved portion including a standing portion extending upward from the outer edge portion of the motor fixing portion and an upper surface portion extending radially outward from an upper end of the standing portion, a plurality of openings positioned below the blades being defined by the curved portion, the peripheral portion, and the ribs.
 2. The blower fan of claim 1, further comprising a sidewall portion arranged to cover sides of the blades, the sidewall portion including a lower end portion fixed to the peripheral portion.
 3. The blower fan of claim 1, further comprising an upper plate portion positioned above the motor unit and the blades, the upper plate portion being made of metal or resin.
 4. The blower fan of claim 2, further comprising an upper plate portion positioned above the motor unit and the blades, the upper plate portion being made of resin and continuously joined to the sidewall portion.
 5. The blower fan of claim 3, wherein the upper plate portion includes an intake port axially overlapping with the blades and the motor unit.
 6. The blower fan of claim 1, wherein the ribs extend radially outward from the upper surface portion of the curved portion.
 7. The blower fan of claim 3, wherein the ribs are angled downward as the ribs extend radially outward.
 8. The blower fan of claim 1, wherein the curved portion further includes a descending portion extending down from a radial outer end portion of the upper surface portion, the ribs extending radially outward from a lower end of the descending portion.
 9. The blower fan of claim 6, wherein the ribs are perpendicular or substantially perpendicular to the center axis.
 10. The blower fan of claim 1, wherein the ribs extend radially outward from the motor fixing portion, the curved portion being provided in the outer edge portion of the motor fixing portion between the ribs.
 11. The blower fan of claim 1, wherein each of the blades includes a lower edge including a straight portion extending from the outer surface of the rotary unit in a direction perpendicular or substantially perpendicular to the center axis, the upper surface portion including a radial outer end portion radially positioned between a radial outer end point of the straight portion and an outer surface of the rotor magnet or radially positioned to coincide with the outer surface of the rotor magnet.
 12. The blower fan of claim 11, wherein the radial outer end portion of the upper surface portion is positioned radially between the outer surface of the rotary unit and the outer surface of the rotor magnet or radially positioned to coincide with the outer surface of the rotary unit or the outer surface of the rotor magnet.
 13. The blower fan of claim 1, wherein each of the blades includes a lowermost portion positioned lower than the upper surface portion of the curved portion.
 14. The blower fan of claim 13, wherein the motor fixing portion is positioned higher than the peripheral portion.
 15. The blower fan of claim 1, wherein the curved portion includes a portion extending upward from a radial outer end portion of the upper surface portion.
 16. The blower fan of claim 15, wherein the portion extending upward from the radial outer end portion of the upper surface portion is positioned radially outward of the rotor holder.
 17. The blower fan of claim 1, wherein the motor unit further includes a circuit board arranged above the motor fixing portion, the motor fixing portion including hole portions or cutout portions into which electronic parts mounted to the circuit board are inserted.
 18. The blower fan of claim 1, wherein the motor unit further includes a circuit board arranged above the motor fixing portion, the outer edge portion of the motor fixing portion including a curved portion nonexistence region in which the curved portion is not provided, the circuit board including an integrated circuit positioned within the curved portion nonexistence region. 